Possible transmission issue

[watts597]

Hello Forum! I am new to this forum and new with my used 2007 Chevy Silverado. I haven't had a truck in about 10 years and my last Chevy truck was a 1973 C30. I consider myself a good forum contributor and will be here since my new purchase has plenty of mysteries that needs be solved.

 

Well, to the point. When driving on the highway at highway speeds (70mph) and under power the truck runs and sounds fine but once I'm holding the speed on level ground there seems to be a vibration (low rumble). If i increase speed a little the vibration and noise goes away. I've noticed it at all lower speeds but its less pronounced.

 

It feels and sounds like a quite engine break. It by no means is dragging the truck slower but its definitely there.

 

It reminds of a slight down shift noise but there really isn't any drag nor is the transmission down shifting. I don't feel like I have to accelerate because I'm slowing. I do find myself accelerating to make it go away.

 

Anyway, here are my vitals:

 

2007 Chevy Silverado LT

5.3 L LY5

2 WD

Tow Package

116K Miles

Trans pan leak (not bad)

 

I plan to drop the pan this weekend, service, and fix the leak. Any help, opinions or comments is welcome and greatly appreciated!

 

Thank you,

Watts

[It's Tim]

Driveshaft center support bearing.